The typical sprinkler head includes a body or frame having an opening connected to the water line. The frame also includes a pair of arms which extend outwardly and are joined together at a junction. A cap encloses the opening in the frame and a releasible mechanism interconnects the cap and the junction and maintains the cap in a closed position. The releasable mechanism may take the form of a frangible glass bulb, or alternately, a lever mechanism including a fusible metal, such as solder. When the release mechanism is exposed to a predetermined elevated temperature, the mechanism will release, enabling the water pressure to dislodge the cap, and the water will then be directed against a deflector mounted on the junction which will deflect or spray the water outwardly in the desired spray pattern.
It has been found that when the frangible bulb ruptures to release the cap, the water pressure will force the cap axially and the cap has a tendency to lodge against the arms of the frame with the result that the water cannot contact the deflector and the desired spray pattern is not obtained.
Because of this, attempts have been made in the past to include an ejection device with the sprinkler head, so that the cap will be moved laterally as it is released by the water pressure and will not hang up on the arms of the frame. In this regard, it has been proposed to machine off-centered grooves in the upstream surface of the cap, so that the center of mass of the cap is offset from its axis. However, the machining operation is expensive and it is necessary to properly orientate the machined grooves when assembling the sprinkler head, which is a tedious, labor intensive operation.
It has also been proposed to connect a plastic member to the upstream surface of the cap having an inclined upstream facing surface. With this construction, when the cap is released, the water pressure acting against the inclined surface is intended to deflect the cap slightly laterally. However, it has been found that the time required for movement of the cap from its closed position to a position where it engages the arms is extremely short, with the result that the water pressure acting on the inclined surface does not have sufficient time to move the cap laterally.
Other attempts to influence the discharge of the cap have included a wire form which is attached to the frame and bears against the cap. The biasing pressure of the wire form, on release of the cap, will tend to move the cap laterally. However, a wire form is expensive and is difficult to assemble with the sprinkler head and also is not aesthetically pleasing.
A further attempt to influence the discharge of the cap has involved the riveting of a small lug in a slot in the frame with the edge of the lug engaging the side of the cap. However, this construction is expensive requiring two additional parts and also involves considerable labor for assembly.